OK, I checked this out, and here is what I found. The Classic Ultimate Shadows were introduced in 2003, produced through 2005, as they are absent in the 2006 catalog. The regular production models were only produced in WSM's and WSSM's. The non-catalogued limited run of .243/7-08/.308 was probably manufactured in 2006. I know I bought my two in 2006. I don't know how many of each was produced. I don't know if these were produced as a special order for some distributor, or if Winchester decided to produce them on their own. I have seen exactly one of each chambering in this limited run. These all had the standard contour barrels, not the Featherweight contour barrels. The serial number on your rifle is only about 20 numbers higher than my 7-08. There, that's about all I know!
I would keep the original stock, that way the rifle could be put back to original. But, that's just me! I am a hoarder of the first rate, and I even have extra factory stocks for many of my M70's!
I would be definitely interested to hear how this rifle shoots. My money is on that it's a darn good shooter!
Good luck!